Auxiliary Panel Optical Path for In-Display Fingerprint Sensing
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Solution Overview
Problem
Liquid crystal displays face challenges in accurate fingerprint identification due to low light transmittance and interference from ambient light, resulting in a small difference in light energy between fingerprint valleys and ridges, making it difficult to achieve precise identification.
Innovation Solution
A display apparatus with a display panel and an auxiliary panel that includes light transmitting regions and shielding regions, where the auxiliary panel is designed to form apertures or lenses, allowing light from an object to pass through and form an image on photosensitive sensors, reducing interference and enhancing identification accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical fingerprint identification is implemented using a liquid crystal display, then fingerprint identification can be performed using the display structure, but the light energy reaching the photosensor is very low due to low transmittance of the liquid crystal layer
Solution Approach 1:
The display panel is divided into two independent regions: a display region for showing images and an identification region for fingerprint sensing. This segmentation allows the identification region to be optimized for light transmission without compromising the display quality of the display region, thereby increasing light energy reaching the photosensor while maintaining fingerprint identification capability
Solution Approach 2:
The patent introduces a new spatial dimension by adding an auxiliary panel above the display panel, creating a multi-layer structure. This auxiliary panel with light transmitting regions forms an optical path that directs light from the object through the display panel to the photosensor, effectively adding a new dimension to the light transmission path and increasing the light energy reaching the photosensor
2Reliability
If the photosensor receives diffused light from the finger, then fingerprint identification can be performed, but the photosensor only receives a very small part of the diffused light beam
Solution Approach 1:
The auxiliary panel acts as an optical intermediary between the object and the photosensor. Its light transmitting regions guide and concentrate the diffused light from the finger onto the photosensor, effectively mediating the light path to ensure that more light energy reaches the photosensor while maintaining the fingerprint identification capability
3Ease of operation
If ambient light is present during fingerprint identification, then the identification process can proceed, but interference from ambient light reduces identification accuracy
Solution Approach 1:
The auxiliary panel implements local quality control by having specific light transmitting regions positioned precisely over the identification region. This localized light transmission design allows ambient light to be blocked in non-identification areas while permitting necessary light transmission in the identification region, thereby reducing ambient light interference without compromising the ease of operation
Solution Approach 2:
The display panel is segmented into a display region and an identification region, with the auxiliary panel's light transmitting regions aligned with the identification region. This segmentation isolates the fingerprint sensing area from ambient light interference in the display region, improving measurement precision while maintaining operational continuity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves the accuracy of fingerprint identification by increasing the intensity of diffused light and blocking ambient light, allowing for precise object identification within the display region without the need for a separate identification area, thus achieving a narrow frame design and cost savings.
Implementation Method 1
light from an object positioned above the auxiliary panel passes through the light transmitting regions and forms an image of the object on the photosensitive sensors
Implementation Method 2
after a light from a backlight of the liquid crystal display reaches a finger, the light is diffused at the finger, and a portion of diffused light is received by a photosensor
Implementation Method 3
the light energy of the light diffused by the valley is lower than the light energy of the light diffused by the ridge, and the fingerprint identification is carried out based on such difference
Data Source
AI summary
A display apparatus and a driving method thereof are provided. The display apparatus includes a display panel, a plurality of photosensitive sensors spaced from each other are in a display region of the display panel, an auxiliary panel is on a light emergent side of the display panel, the auxiliary panel has a plurality of light transmitting regions spaced from each other, a light shielding region is between the light transmitting regions adjacent to each other, and light from an object positioned above the auxiliary panel passes through the light transmitting regions and forms an image of the object on the photosensitive sensors.